Randomly a week or so ago I noticed a swelling under my skin. When swollen, it felt sore to the touch. The swelling went down after a couple days. It was on the ventral side of the penis a few mm lateral of the center line. It is about the size/shape of a grain of rice and sort of feels like a tube but I don't think it is a blood vessel. Is this something worry about? It could have always been there an now i notice it just because it was swollen. I am not active so Im positive it isn't an std btw.